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Seniors Health 2006-07(hearing) |
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Whistling Feedback
Seniors Choice Newsmagazine, July 2006
By Colin VanBergen
What can I do about the whistling (feedback) produced by my hearing aids?
There are two types of acoustic feedback: that produced internally from the hearing aid - indicating a device in need of repair; and the more common external feedback produced by a leakage of amplified sound out of the ear canal and back into the microphone of the hearing aid. Feedback that occurs when the hearing aid is being inserted or removed or when your hand is cupped near the device is common, and does not necessarily signal the need for action. If however, you experience feedback when you speak, chew, yawn or change position, you need to consult your audiologist. Feedback is more likely to occur in smaller hearing devices because the microphone is closer to the area at which the sound comes out into the ear. So, a behind-the-ear style may be less likely to produce feedback than in in-the-canal style device. Usually, external feedback can be corrected by:
1. properly reinserting the hearing aid or earmold
2. remaking the earmold (or in-the-ear shell)
3. plugging, or reducing the diameter of any vents (holes)
4. reducing the amount of high frequency gain, (typically an unacceptable trade-off because of the resultant loss of high frequency hearing)
5. altering the sound by means of filters in the hearing aids or changes in the way the devices are programmed
6. adding a "canal lock" (a piece of plastic) to better hold canal hearing aids in place so they don't work their way out of the ear canal as you chew
Since the onset of hearing aids becoming digital (which has been about 8 years now), hearing aid manufacturers have made many attempts in designing a hearing aid, which would eliminate or reduce feedback. The difficulty they had with this process was that any method they came up with to reduce feedback would have a negative impact on the performance of the hearing aid. Essentially, proper amplification of sounds was compromised in order to get rid of the feedback. But as time has passed, most of the manufacturer's have now figured out a way to eliminate feedback (through the means of a process called phase cancellation) without compromising sound quality. This technology is currently in many hearing aids that are being dispensed today. While feedback is still an issue that needs to be dealt with on a periodic basis, it does not rear its head nearly as often as it once did.
If you have any hearing-related questions please send them to me at
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or submit them directly to me at either of my offices. Colin VanBergen is a clinical audiologist, and manages both the Kelowna and Westbank offices of the Okanagan Hearing Clinic. |
